Isolation and characterization of thermotolerant bacterium utilizing ammonium and nitrate ions under aerobic conditions.

A thermotolerant bacterium, identified as Bacillus licheniformis, completely utilized 0.1% (w/v) NH(4)NO(3) at 30 and 50 degrees C under aerobic condition. The addition of 0.5 mM Fe(2+) to the NH(4)NO(3 )medium markedly promoted the utilization of NH (4) (+) and NO (3) (-). At 50 degrees C, of total nitrogen originally provided, 24% was taken up into the cells and 20% remained in the culture supernatant. Residual nitrogen (56%) was probably removed into the atmosphere. The cell extracts contained enzymes involved in denitrification. GC-MS demonstrated that NH (4 ) (15) NO(3) had been converted to (15)N(2)O. These results indicate that the strain has denitrification ability under aerobic condition.